Project Summary/Abstract Insomnia disorder occurs in 10-20% of the population and confers a >2-fold increased causal risk of incident cardiovascular disease (CVD) based on our recent Mendelian randomization studies. To identify new therapeutic targets for insomnia that ameliorate CVD risk, it is important to dissect the causal pathophysiology of insomnia and distinguish whether increased CVD risk arises from shared causal mechanisms or specific cardiovascular insults induced by the insomnia state. This proposal is motivated by the research question: how does insomnia lead to increased CVD and what specific mechanisms of insomnia should be targeted to prevent or delay CVD? We found 57 genome-wide significant genetic loci for insomnia and established robust causal links with CVD, but need improved understanding of specific shared causal pathways and mechanistic links in order to move towards personalized, effective therapies. Recent model organism studies describe specific mechanistic links between sleep, immunity, atherosclerosis and cardiovascular disease that we can also test for disease relevance in people to decipher convergent mechanisms. Thus, here we propose to leverage genome-sequencing and integrative multi-omics in multi-ethnic samples from TopMed and exome sequencing in UK Biobank with focused functional studies of sleep and cardiovascular function in Drosophila to find the causal genes and identify mechanisms that causally link insomnia to CVD. We propose the following Specific Aims: 1) To pinpoint causal genes at 57 established insomnia genetic loci and dissect underlying disease mechanisms and pathways in humans (NHLBI TopMed and UK Biobank). Multi-ethnic fine-mapping and rare variant analysis will pinpoint causal genes and soft clustering analysis informed by multi-trait associations will identify heterogeneous insomnia disease mechanisms and subtypes. 2) To test the consequence of the loss of function of the Drosophila orthologs of causal human insomnia genes on sleep and cardiovascular function. Phenotypic effects and gene expression patterns will be systematically characterized to unravel important functional pathways and networks. 3) To test the impact of perturbed sleep (disrupted or improved) on incidence and progression of CVD in Drosophila using small molecule-, genetic- mechanical perturbation and time-restricted feeding and using integrative multi-omics in humans (NHLBI TopMed). Our project will shortlist therapeutically-relevant genes and pathways that link insomnia, sleep and CVD.